Bistable diaphragm relay



P 1969 s. WOODHEAD 3,470,505

BISTABLE DIAPHRAGM RELAY Filed Sept. 29, 1967 v 2 Sheets-Sheet 1 HS, WOOD/4540' Inventor Attorney p 30. 1969 H. s. WOODHEAD 3,470,505

I BISTABLE DIAPHRAGM RELAY Filed Sept. 29, 1967 2 Sheets-Sheet 2 LL w I 23 2s v gi 24 4 United States Patent 3,470,505 BISTABLE DIAPHRAGM RELAY Harry Stanley Woodhead, Harlow, England, assignor to International Standard Electric Corporation Filed Sept. 29, 1967, Ser. No. 671,762 Claims priority, application Great Britain, Oct. 21, 1966, 47,148/ 66 Int. Cl. HOlh 51/22 US. Cl. 335-83 17 Claims ABSTRACT OF THE DISCLDSURE A polarized magnetically latching miniature diaphragm relay in which a permanent magnet is mounted in line with the core of the winding at the end remote from the diaphragm. An arcuate collar around the core between the winding and the magnet provides a magnetic shunt path to the cover, lowering the necessary ampere turns required to release the contacts and reducing the demagnetizing effect on the permanent magnet.

This invention relates to electromagnetic contactmaking relays.

According to the invention such a relay includes a permanent magnet, an outer magnetic member, an inner magnetic member passing through an aperture in the outer magnetic member and electrically insulated therefrom, and a resilient diaphragm of magnetic material secured at its periphery to the outer magnetic member and in its unstressed state spaced from the inner magnetic member constituting contacts of the relay and being capable of being brought into contact with each other by virtue of the flux threading a principal magnetic circuit including the said two magnetic members and the permanent magnet, the magnitude of which flux at least across the contacts may be altered by the energisation of an actuating winding disposed around an element in said principal magnetic circuit.

Other features of the invention will be evident from the following description of a polarised magnetically latching electromagnetic relay embodying the invention in a preferred form.

For the purposes of this specification the term polarised magnetically latching electromagnetic relay is defined to mean a bistable relay incorporating a magnetic circuit which, while the actuating winding is not energised, is threaded with magnetic flux having values corresponding to the operative and released positions of the contacts such as to enable the contacts to remain in either of these positions without the energising of the actuating winding.

The description refers to the accompanying drawings in which:

FIGURE 1 shows a longitudinal section of the relay along its centre line.

FIGURE 2 shows a cross section of the relay in the plane marked II-II in FIGURE 1,

FIGURE 3 shows a cross section of the relay in the plane marked IIIIII in FIGURE 1,

FIGURES 4 and 5 show a cross section of the relay in the plane marked 1VIV in FIGURE 1 with the shunt member in positions of maximum and minimum reluctance respectively.

With reference to the accompanying drawings the contact assembly of the relay includes a mild steel annulus having a nickel-iron rod 11 secured within its central aperture and electrically insulated therefrom by an impervious annular seal 12, for example of glass. The annulus 10 and the rod 11 form part of the magnetic circuit of the relay. A shallow hole is drilled into one end ice of the rod 11 to leave the annular end face 13 which forms one of the two co-operating contacts of the relay. The armature and the other contact of the relay are formed by a resilient diaphragm 14 of magnetic material which is secured at its periphery to the mild steel annulus 10 by means of a closure member or end cap 15 which is itself sealed around its periphery to the annulus 10. A spacing ring 16 ensures that when the diaphragm 14 is in the unstressed state a suitable isolating gap remains between the central contact-making area of the diaphragm and the co-operating end face 13 of the rod 11; the correct spacing of the diaphragm may alternatively be obtained by suitably profiling the end face of the annulus 10.

It will be seen that the contact pair formed by the diaphragm 14 and the end face 13 of the central rod 11 are contained in a sealed enclosure, and that the major sealing operation involved in making the enclosure, the sealing of the rod 11 within the annulus 10, can be performed as the first manufacturing step in the construction of the relay so that the relatively high sealing temperature required cannot effect items such as the diaphragm 14 or the relay winding which are added to the assembly at a later stage. The end cap 15 can be secured to the annulus 10 by low temperature soft soldering.

The diaphragm 14 is provided with a number of slots 17, of length much greater than their width, that serve to increase the resiliency of the diaphragm and thus to reduce the stress necessary to distort it to make contact with the co-operating contact surface 13. The slots 17 are in the form of arcs of circles and are so interconnected that the ceneral contact-making area 18 of the diaphragm is connected with its peripheral area 19, by which it is secured to the annulus 10 by three tongues of metal 20, of width small relative to their length. This arrangement allows the central area of the diaphragm considerable freedom of movement while at the same time ensuring that when it is attracted to the rod 11 by energisation of the associated magnetic circuit it moves substantially normally into contact with the end face of the tube.

The diaphragm 14 must, of course, be made of a magnetical material such as nickel-iron alloy, and in order to provide a good electrical contact it may be plated over all or part of its area with a suitable noble metal such as palladium. A similar layer may be plated on to the end face 13 of the rod 11. Besides forming the contact surface the protective layer or layers also provide the necessary magnetically insulating spacer between the contact members.

Relay contact terminals 23 and 24 are aflixed to the curved surfaces of the annulus 10 and the rod 11 respectively.

The rod 11 forms part of the inner magnetic member of the relay and is considerably longer in the axial direction than the corresponding outer member formed by the annulus 10. A polyester sleeve 25 is attached to the projecting part of the rod 11 by heat shrinking, and this serves to electrically insulate the rod 11 from the rest of the inner magnetic member formed by a nickel-iron sleeve 26, which is a slide fit over the polyester sleeve 25. The remaining part of the inner magnetic member is formed by a cylindrical permanent magnet 27, which is attached to the nickel-iron sleeve 26.

The actuating winding 21 of the relay is wound on an insulating former 22 which surrounds the rod 11 and the sleeves 25 and 26, the diameters of the winding 21 and of the circular part of the former 22 being made not greater than the outside diameter of the annulus 10. The ends of the winding are soldered to two winding terminals 28 which project through the base of the former 22, and a slot is cut in the end face of the former 22 adja- 3 cent the annulus 10 to accommodate the contact terminal 24.

The principal magnetic circuit formed by the permanent magnet 27, the nickel-iron sleeve 26, the rod 11 the diaphragm 14 and the annulus 10, is completed by an end plate 30 which is attached to the permanent magnet 27 and by the magnetic material of an outer cover member 29 which is sprung over the annulus 10 and the end plate 30.

This principal magnetic circuit is modified by the existence of a magnetic shunt member 31, having the form of a sector of an annular cylinder with its outer diameter less than the outer diameter of the annulus 10. The surface of the inner diameter is rigidly attached to the nickel-iron sleeve 26 so that it lies between the permanent magnet 27 and the actuating winding 21. The shunt member 31 co-operates, via a small air gap, with part of the outer cover member to provide a subsidiary magnetic circuit which includes the permanent magnet but shunts the contacts, formed by the diaphragm 14 and the end face 13 of the rod 11, and that part of the rod 11 lying within the actuating winding 21.

During manufacture, the assembly of the end plate 30, the permanent magnet 27, the nickel-iron sleeve 26 and the shunt member 31, is capable of rotation about the polyester sleeve 25 whereby the reluctance of the subsidiary magnetic circuit may be adjusted to a desired value. The positions of maximum and minimum reluctance are shown in FIGURES 4 and 5 respectively. In this embodiment it is preferred to arrange the magnetic components so that when the diaphragm is in its released position and the actuating winding is not energised there is more magentic flux in the shunt than in the diaphragm. After adjustment the assembly of end plate 30, permanent magnet 27, nickel-iron sleeve 26 and shunt member 31, is held in position by cementing the end plate 30 to the outer cover member 29. The identification of the components of the relay is completed with the mention of two insulating washers 32 and 33. One washer, 32, serves to protect the contact terminal 24 from accidental contact with the annulus 10, and the other washer, 33, serves to protect the winding connections to the winding terminals 28 from accidental contact with the shunt member 31.

The spacing of the pins forming the contact terminals and the winding terminals may be such as to comply with the normal track spacing for printed circuit assemblies, the small physical dimensions of the relay (a practical realisation of the arrangement shown in the drawings being approximately 0.9 inch long and 0.4 inch in diameter) rendering it particularly suitable for such applications.

In the construction of this relay the use of a shunt member 31 providing a subsidiary magnetic circuit including the permanent magnet but shunting the contacts and the part of the rod 11 lying Within the actuating winding 21 gives rise to a number of advantages. Firstly it enables the adjustment, during manufacture of the relay, of the flux across the relay contacts. Secondly it shunts the permanent magnet from the demagnetising field produced when the operating winding is energised in such a way as to reduce the flux across the contacts so as to effect their separation. Thirdly it lowers the reluctance of the magnetic circuit seen by the actuating winding thereby enabling a smaller number of ampere-turns to cause the operation or release of the relay. And fourthly it causes a greater change of flux across the contacts between the released and the operated positions because some of the flux from the permanent magnet is switched from threading the shunt to threading the contacts and this results in an improvement of the latching properties of the relay.

It is to be understood that the foregoing description of specific examples of this invention is made by way of example only and is not to be considered as limitation on its scope.

What is claimed is:

1. An electromagnetic polarized magnetically latching contact making relay including an actuating winding, an outer magnetic member, an inner magnetic member terminating in first and second ends and passing through an aperture in the outer magnetic member and electrically insulated therefrom, a resilient diaphragm of magnetic material secured at its periphery to the outer magnetic member and in its unstressed state spaced from the first end of the inner magnetic member, a permanent magnet held in alignment near the second end of the inner magnetic member, the diaphragm and the inner magnetic member constituting contacts of the relay which once brought into contact with each other are capable of holding in contact with each other by virtue of the flux threading a principal magnetic circuit, the principal magnetic circuit including the said two magnetc members and the permanent magnet, the total magnitude of the flux across the contacts being subject to alteration by the energization of the actuating winding disposed around an element in said principal magnetic circuit, and the contacts being subject to a change in status accordingly.

2. A relay as claimed in claim 1 wherein the actuating winding is disposed around the inner magnetic member.

3. A relay as claimed in claim 2 wherein the permanent magnet forms part of the inner magnetic member and the actuating winding lies between the permanent magnet and the contacts.

4. A relay as claimed in claim 1 having a magnetic shunt member providing a subsidiary magnetic circuit which includes the permanent magnet but shunts the con tacts and the magnetic material within the actuating windmg.

5. A relay as claimed in claim 4 wherein said subsidiary magnetic circuit includes a gap between magnetic materials at one end of the shunt member such that at least during the manufacture of the relay the reluctance of the subsidiary magnetic circuit may be adjusted by the movement of the shunt member.

6. A relay as claimed in claim 4 wherein at least while the diaphragm is in its released position and 'while the actuating winding is not energized there is more magnetic flux in the shunt member than in the diaphragm.

7. A relay as claimed in claim 6 which is a polarized magnetically latching relay.

8. A relay according to claim 1 wherein the diaphragm has therein two or more apertures situated between its peripheral and contact-making areas and so formed that their presence reduces the stress necessary to cause the diaphragm to make contact with the inner magnetic member.

9. A relay according to claim 8 wherein the said apertures are slots of width small relative to their length.

10. A relay according to claim 8 wherein the said apertures are so formed that the contact making area of the diaphragm is connected with its peripheral area by two or more tongues of width small relative to their length.

11. A relay according to claim 8 wherein at least the contact making area of the diaphragm has thereon a layer of a noble metal.

12. A relay according to claim 1 wherein the surface of the inner magnetic member that co-operates with the diaphragm has thereon a layer of a noble metal.

13. A relay according to claim 1 wherein the inner magnetic member is connected with the outer magnetic member by an electrically insulated impervious seal.

14. A relay according to claim 6 wherein the diaphragm is contained in a sealed enclosure formed in part by a closure member sealed in its periphery to the outer magnetic member.

15. A relay according to claim 1 wherein the inner mag netic member extends beyond the outer magnetic member on one side thereof and is surrounded by an operating winding of the relay.

16. A relay according to claim 1 wherein the contactmaking surface of the inner magnetic member has the form of a plane annulus.

17. An electromagnetic contact making relay including an actuating winding, an outer magnetic member, an inner magnetic member terminating in first and second ends and passing through an aperture in the outer magnetic member and electrically insulated therefrom, a resilient diaphragm of magnetic material secured at its periphery to the outer magnetic member and in its unstressed state spaced from the first end of the inner magnetic member, a permanent magnet held in spaced relation from the second end of the inner magnetic member, the diaphragm and the inner magnetic member constituting contacts of the relay and being capable of being brought into contact with each other by virtue of the flux threading a principal magnetic circuit, the principal magnetic circuit including the said two magnetic members and the permanent magnet, the magnitude of which flux at least across the contacts may be altered by the energization of the actuating winding disposed around an element in said principal magnetic circuit, a magnetic shunt member providing a subsidiary magnetic circuit which includes the permanent magnet but shunts the contacts and the magnetic material within the actuating winding, said subsidiary magnetic circuit including a gap between magnetic materials at one end of the shunt member such that at least during the manufacture of the relay the reluctance of the subsidiary magnetic circuit may be adjusted by the movement of the shunt member, the shunt member lying between the magnet and the actuaing winding as a sector of an annular cylinder and co-operating with a part of an outer cover magnetic member which forms part of the principal magnetic circuit and which outer cover member does not completely encircle the inner magnetic member such that the reluctance of the subsidiary magnetic circuit may be adjusted at least during manufacture of the relay by the rotation of the shunt about the axis of the inner magnetic member.

References Cited UNITED STATES PATENTS 12/1963 Moser 335229 7/1967 Woodhead 33515l 

